Fuel injector for internal combustion engines



FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES Filed Jan. 15, 1968 M- J.BERLYN Sept, 15, 1970 4 Sheets-Sheet 1 FIG. 7.

Sept. 15, 1970 M. J. BERLYN 3,528,613

FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES Filed Jan. 15, 1968 4Sheets-Sheet 2 Se t. 1 1970 M. J. BERLYN 3,528,613

FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES Filed Jan. 15, 1968 4Sheets-Sheet s MAR T'ln/ ITOH/V BEHLYA/ BaMwvwi-e Ban/mm Sept. 15, 1970M. J. BERLYN Filed Jan. 1968 4 Sheets-Sheet 4 g 2T 1" 29 7 7 7-22 22 .7810 V I 79 52 I 1 21 E g5 United States Patent 3,528,613 FUEL INJECTORFOR INTERNAL COMBUSTION ENGINES Martin J. Berlyn, Leeds, England,assignor to Hailwood & Ackroyd Limited, Leeds, England, a British com-Filed Jan. 15, 1968, Ser. No. 697,687 Int. Cl. Bb 1/32 U.S. Cl. 239453Claims ABSTRACT OF THE DISCLOSURE A fuel injector for internalcombustion engines comprising a nozzle holder formed for mounting in theengine cylinder head and provided with a fuel supply duct, and anassembly of a differential valve, valve guide, loading spring and nozzletip formed as a replaceable unit and clamped to the holder.

This invention relates to fuel injectors for internal combustion enginesand, more particularly, to injectors for diesel engines of theopen-chamber direct-injection type.

In such engines, the use of spring-loaded differentialvalve multipleorifice injectors is now almost universal. No other type of injector hasprovided such generally satisfactory solutions to the problems offormation, dispersion and penetration of the fuel spray in open-chambercombustion spaces. Contemporary injector for openchamber diesel enginesare costly and must be reconditioned at intervals in order to keep themfunctioning satisfactorily. Contemporary injectors, furthermore, requiretwo pipe connections each, one for fuel delivered from the pump and onefor fuel leakoff from the injector back to the inlet side of the pump.This leakoif plumbing is not only an added item of first cost butcomplicates, and increases the cost of servicing the injectors.

Another shortcoming of contemporary injectors is that their functionalcomponents extend from the nozzle tip to the remote end of the nozzleholder so that, when the nozzle holder is axially compressed by thebolts or studs employed from making a gas-tight seal between the holderand its seat in the cylinder head, the settings of the functionalcomponents may be disturbed by axial shortening of the holder. In orderto prevent the application of abusive installation forces to theinjectors, some engine makers incorporate costly and bulky devices tolimit the force it is possible to apply to the nozzle holders.

The object of the present invention is to provide an improved form offuel injector which does not suffer from the above-mentioned defectsassociated with known fuel injectors, said improved injector beingeconomical to produce and involving no substantial service charges inthe maintenance of the injector in eflicient operating condition.

According to the invention the improved fuel injector consisting of anozzle holder formed for mounting in the cylinder head of the engine andincorporating a fuel supply duct, and an injector assembly comprising ahollow body provided with a fuel inlet port and, within said body, aspring-loaded differential valve coacting with a seating to control flowof fuel to a nozzle tip, said body, valve, the valve loading spring andthe nozzle tip being formed as a replaceable unit adapted to be clampedto the nozzle holder with its inlet port in commuication with saidsupply duct.

FIG. 1 shows in section a flanged nozzle holder with an injectoraccording to this invention shown in elevation and clamped in place by aconventional nozzle nut which is show in section,

3,528,613 Patented Sept. 15, 1970 "ice FIG. 2 is a diametral section ofthe injector assembly,

'FIG. 3 is a diametral section of an alternative execution of theinjector assembly,

FIG. 4 is a fragmentary transverse section at 44 of FIG. 3, and

FIG. 5 is a diametral section of another alternative execution of theinjector assembly.

In FIGSQZ, 3 and 5 the left-hand half of each section shows the valve inthe closed position and the right hand half of each section shows thevalve in the fully open position.

Referring first to FIG. 1, there is shown a nozzle holder 6 providedwith a fuel duct 7 and threaded at its lower end to receive a nut 8which serves to clamp an injector assembly 9 by means of its flange 12upon the nozzle holder.

Referring now to FIG. 2, the injector assembly comprises a body 10provided with an opening or port 11 for admission of fuel and anintegral flange 12 by which it is clamped to the nozzle holder, a springchamber 13-, a counterbore 14 and a deformable skirt 15. A coaxial valveguide 16 is provided with a bore 17, a conical seat 18, an enlarged bore19, a flange 20 having a face 21, and transverse ports 22. A spring 23is held between a spring abutment 24 of valve guide 16 and a spring seat25 which is retained on a valve member 26 by semicircular cotters 27 ingroove 28 of valve member 26. The latter has a neck 29, of smallerdiameter than valve stem 30, a conical face 31 and a piston 32 which isa fuel-throttling fit in the enlarged bore 19 of valve guide 16. Anozzle tip 33 is provided with a face 34, a shoulder 35, a sac hole 36and spray orifices 37.

In assembly of the injector a subassembly is first made of valve member26, guide 16, spring 23, spring seat 25, cotters 27 and valve liftadjustment shim 38 and this subassembly is inserted into body 10 untilflange 20 of guide 16 is at the end of counterbore 14 of body 10. Nozzletip 33 is then inserted into counterbore 14 of body 10 until face 34 ofnozzle tip 33' abuts face 21 of flange 20 of guide 16 and deformableskirt 15 of body 10 is then folded over shoulder 35 of nozzle tip 33.

In operation of the injector, fuel from a pump is delivered through duct7 of the nozzle holder and enters at opening 11, flowing through springchamber 13 and by way of radial ports 22 into bore 17. Having forcedvalve 26 open by overcoming the valve-closing bias of spring 23, thefuel passes through enlarged bore 19 into sac hole 36 and through sprayorifices 37.

If piston 32 is a fluid-throttling fit in enlarged bore 19, valve 26reciprocates at high frequency during flow of fuel through the nozzletip, this having a beneficial influence upon the dispersion of the sprayfrom orifices 37 and results in improved combustion of the fuel.

In the modification according to FIGS. 3 and 4 it will be seen that thetransverse ports 22a in valve guide 16 are tangential to bore 17. Thesetangential ports cause a rotary swirl of fuel about the axis of thenozzle which persists in the fuel passing conical face 31 and piston 32of valve 26, and the rate of swirl is increased when the fuel reachessac hole 36 of nozzle tip 33 due to the relatively small diameter of sachole 36, this rotary swirl of the fuel in sac hole 36 breaking up thefuel issuing from orifice 37 into particles of small size. FIG. 3 alsoshows a conical fairing 38 on piston 32 of valve 26 such fairing havingbeen found to improve the injector performance. FIG. 3 also shows analternative fastening, by screw threads, of spring seat 25 to stem 30 ofvalve 26, this fastening method eliminating the need of the semicircularcotters 27 and lift adjustment shim 38. In this execution, the screwthreads are locked by means of an anerobic sealant after the desiredvalve fit adjustment has been made.

FIG. shows an alternative threaded fastening of spring seat 25 to stem30 of valve 26 wherein a grubscrew 39 is employed for locking the screwthreads after the valve lift adjustment has been made. FIG. 5 also showsdiagonal grooves 40 in the piston 32 and fairing 38 of valve 26. Thesegrooves provides a means of creating rotary swirl of fuel in sac hole 36of nozzle tip 33 and may be employed as an alternative to the tangentialports 22a shown in FIGS. 3 and 4.

It will be understood that the injector according to the invention canbe made at a fraction of the cost of contemporary injectors. Itincorporates no lapped fits and its functional parts are permanentlyassembled in a small capsule and this small assembly may be thrown awayand replaced with a new one for less than the cost of reconditioning aconventional injector. Moreover, as the nozzle holder contains nofunctional components, simply a fuel duct, it does not wear out, ischeap to make and requires no servicing. The injector requires only onepipe connection as there is no fuel leakolf, and as the functionalcomponents in the permanently-assembled capsule are isolated frominstallation forces, the settings of this injector are immune fromdisturbance. The improved injector is therefore characterised by lowfirst cost, low operating cost to the user, immunity from maladjustmentdue to deformation, and elimination of leakolf and its concomitantplumbing.

I claim:

1. A fuel injector for internal combustion engines including a nozzleholder having means for mounting said injector in an internal combustionengine cylinder head and incorporating a fuel supply duct; and aninjector assembly comprising a hollow body, a fuel inlet port in saidbody, a differential valve member, valve guiding means having a valveseat, and a bore in the outlet side of said seat, a spring mountedwithin said body and effective to urge said valve member against saidseat, a piston mounted on said valve member and having a fuel throttlingfit within said bore, and a nozzle tip in communication with said bore;said injector assembly being formed as a replaceable unit adapted to beclamped to said nozzle holder with said inlet port in communication withsaid fuel supply duct, and said valve guide being flanged at its lowerend to engage a shoulder on said body, a deformable skirt portion onsaid body which bends over its shoulder-on said nozzle tip to clamp saidtip against the underface of said valve guide and thereby provide apermanent fuel tight assembly of said body, guide and nozzle tip.

2. An injector as claimed in claim 1, wherein the fuel supply ductterminates at the lower face of the nozzle holder, the fuel inlet portbeing located in the upper end of the body of the injector assembly,which body end is also flanged, whereby when the body is clamped by itsflange upon said lower face of the nozzle holder, the fuel supply ductis automatically connected to the fuel inlet port.

3. An injector as claimed in claim 1, including means for creating arotary swirl of fuel in the nozzle tip.

4. An injector as claimed in claim 3 wherein said swirlcreating means isprovided by forming the transverse ports in the wall of the guidesubstantially tangential to the bore of the guide.

5. An injector as claimed in claim 3, wherein said swirl-creating meansconsists of inclined grooves formed in the periphery of the piston ofthe poppet valve.

6. An injector as claimed in claim 1, including a substantially conicalfairing on the underside of the piston of the poppet valve as and forthe purpose set forth.

7. An injector as claimed in claim 1, wherein said valve member is ofthe poppet type and comprises a stem having on its lower end a headprovided with a conical sealing face, said valve guiding means comprisesa tubular valve guide having a conical valve seating for engagement withthe conical face on said valve member and a number of transverse portsin the wall of said tubular guide to allow fuel to pass from the bodyinto the guide through the valve past said piston to said nozzle tipwhen said valve is open, and said nozzle tip is perforated and locatedat the lower end of said body.

8. An injector as recited in claim 1, comprising an abutment on saidvalve guiding means and a spring seat on said valve member, said springbeing interposed between said abutment and said spring seat andinterchange: able means being provided for determining the degree oftravel of said spring seat relative to said valve guide and therebydetermining the degree of lift of said valve member.

9. An injector as recited in claim 7 wherein said swirl creating meansis provided by forming the transverse ports in the wall of the guidesubstantially tangential to the bore of said guide.

10. A fuel injector for internal combustion engines including a nozzleholder having means for mounting said injector in an internal combustionengine cylinder head and incorporating a fuel supply duct; an injectorassembly comprising a hollow body and a fuel inlet port in said body;valve guide means monuted in said body and having a guide bore, a valveseating face and port means communicating between said body and saidguide bore upstream of said seating face; a differential valve memberincluding a stem slidable in said guide bore, a valve seat section forengaging said seating face, and a reduced neck portion adjacent saidport means and connecting said stem and valve seat section; a springmounted within said body and effective to urge said valve seat sectionagainst said seating face; an enlarged cylindrical bore on the outletside of said valve seating face; a cylindrical piston connected to saidvalve seat section and having a fuel throttling fit within said enlargedbore; a nozzle tip in communication with said enlarged bore; saidinjector assembly being formed as a replaceable unit adapted to beclamped to said nozzle holder with said fuel inlet port in communicationwith said fuel supply duct.

References Cited UNITED STATES PATENTS 2,154,875 4/ 1939 Streby 239-45 32,951,647 9/1960 Dreisin 2.39-453 3,156,414 11/1964 Dressler 239--453LAURENCE M. GOODRIDGE, Primary Examiner US. Cl. X.R. 123-32

